A Bayesian approach to the optimization reliability costs

2013 ◽  
Vol 10 (6) ◽  
pp. 577-584
Author(s):  
S. Beleulmi ◽  
A. Bellaouar ◽  
M. Lachi
Keyword(s):  
Bayesian Estimation ◽  
Failure Rate ◽  
Bayesian Approach ◽  
A Priori ◽  
Reliability Testing ◽  
Classical Approach ◽  
Electronic Components ◽  
Virtual Testing ◽  
Bayesian Techniques ◽  
The Cost

The lack of reliability testing in a project finds its reason in financial considerations and deadlines. In this context, Bayesian techniques find their applications as they contribute to a significant reduction in the amount of reliability testing based on the classical approach, with the knowledge of the reliability data on a priori relevant components. This paper is devoted to a Bayesian approach to the optimization reliability costs of tests conducted on the electronic components installed in a lift. The Bayesian estimation provides a failure rate of 1,795·10-6 failure/hr to 60% confidence instead of 2,771·10-6 failure / hr after testing. A gain of 64, 77% in terms of time and therefore the cost of testing will be reduced considerably. When the number of failures increases (K0 = 2; 3 and 5), the real tests are not added to virtual testing and a decrease in time to be won has been recorded.

scholarly journals Solar Module Integrated Converters as Power Generator in Small Spacecrafts: Design and Verification Approach

Aerospace ◽  
2019 ◽  
Vol 6 (5) ◽  
pp. 61 ◽  
Author(s):  
Jesus Gonzalez-Llorente ◽  
Aleksander A. Lidtke ◽  
Ken Hatanaka ◽  
Ryo Kawauchi ◽  
Kei-Ichi Okuyama
Keyword(s):  
Failure Rate ◽  
Rapid Development ◽  
Electrical Power ◽  
Solar Array ◽  
Electrical Power System ◽  
Solar Module ◽  
Small Satellites ◽  
Frequent Failure ◽  
Verification Process ◽  
The Cost

As small satellites are becoming more widespread for new businesses and applications, the development time, failure rate and cost of the spacecraft must be reduced. One of the systems with the highest cost and the most frequent failure in the satellite is the Electrical Power System (EPS). One approach to achieve rapid development times while reducing the cost and failure rate is using scalable modules. We propose a solar module integrated converter (SMIC) and its verification process as a key component for power generation in EPS. SMIC integrates the solar array, its regulators and the telemetry acquisition unit. This paper details the design and verification process of the SMIC and presents the in-orbit results of 12 SMICs used in Ten-Koh satellite, which was developed in less than 1.5 years. The in-orbit data received since the launch reveal that solar module withstands not only the launching environment of H-IIA rocket but also more than 1500 orbits in LEO. The modular approach allowed the design, implementation and qualification of only one module, followed by manufacturing and integration of 12 subsequent flight units. The approach with the solar module can be followed in other components of the EPS such as battery and power regulators.

scholarly journals Model calculations of posterior reliability indicators for the proposal of the maintenance system

2018 ◽  
Vol 157 ◽  
pp. 08003 ◽  
Author(s):  
Jana Galliková ◽  
Vladimír Stuchlý ◽  
Roman Poprocký ◽  
Peter Volna
Keyword(s):  
A Priori ◽  
Weibull Model ◽  
Calculation Methods ◽  
Optimal Process ◽  
Model Calculations ◽  
Maintenance System ◽  
Reliability Indicators ◽  
Technical Practice ◽  
Reliability Methods ◽  
The Cost

Designing the content and scale of maintenance of machines and equipment by a priori and posterior reliability methods in considered crucial to reducing the cost of the machine's life cycle, maintaining high operational readiness and reducing the consequences of failures. In the presented paper, attention is paid to the analysis of the calculation methods of posterior reliability for calculation indicators of reliability and to the use of the specified Weibull model for reliability calculations. The obtained results are further developed for models of optimal process calculations to perform scheduled maintenance interventions. Calculations of the other RAMS (reliability, availability, maintainability and safety) indicators that are critical to the design of an optimal engineering design with regard to maintenance and which do not receive sufficient attention in technical practice are also assessed.

DETECTION OF TRACKS IN AERIAL PHOTOS BY THE GIBBS SAMPLER

2003 ◽  
Vol 17 (01) ◽  
pp. 1-16 ◽  
Author(s):  
A. TETERUKOVSKIY
Keyword(s):  
Prior Knowledge ◽  
Cell Size ◽  
Bayesian Approach ◽  
Gibbs Sampler ◽  
Prior Information ◽  
A Priori ◽  
A Priori Knowledge ◽  
Gray Level ◽  
Aerial Photos ◽  
Positive Results

A problem of automatic detection of tracks in aerial photos is considered. We adopt a Bayesian approach and base our inference on an a priori knowledge of the structure of tracks. The probability of a pixel to belong to a track depends on how the pixel gray level differs from the gray levels of pixels in the neighborhood and on additional prior information. Several suggestions on how to formalize the prior knowledge about the shape of the tracks are made. The Gibbs sampler is used to construct the most probable configuration of tracks in the area. The method is applied to aerial photos with cell size of 1 sq. m. Even for detection of trails of width comparable with or smaller than the cell size, positive results can be achieved.

Determination of Hydraulic Permeability Based on the Measurements of Outflow

2015 ◽  
Vol 3 ◽  
pp. 105-116
Author(s):  
Jozef Kačur ◽  
Jozef Minár
Keyword(s):  
Unsaturated Flow ◽  
Dimensional Space ◽  
A Priori ◽  
Hydraulic Permeability ◽  
Infinite Dimensional ◽  
Tuning Parameters ◽  
Finite Dimensional ◽  
Partially Saturated Porous Media ◽  
The Cost

In this paper we present a method for the determination of the hydraulic permeability for flow in partially saturated porous media. The dependence of hydraulic permeability on effective saturation is not assumed to be a member of any specific finite dimensional class of functions (e.g. vanGenuchten-Mualem, Burdin-Mualem, Brook-Corey). Instead, an infinite dimensional space of functions with limited a priori assumptions (e.g. smoothness, monotonicity) is considered. Consequently, we face a more challenging problem compared to the finite-dimensional case, in which only few tuning parameters need to be determined. We consider the case of 1D unsaturated flow and assume that the data are collected at the outflow of the sample. The hydraulic permeability is determined in an iterative way. We minimize the cost functional reflecting the discrepancy between the measured and computed data. In doing so, we use the Gateaux differential to obtain the direction of the descent.

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